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Initialise scatter/gather list in sg driver
[linux-2.6/libata-dev.git] / net / sched / sch_teql.c
blob421281d9dd1d3f9103b17c71b68b0d927d3807da
1 /* net/sched/sch_teql.c "True" (or "trivial") link equalizer.
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU General Public License
5 * as published by the Free Software Foundation; either version
6 * 2 of the License, or (at your option) any later version.
7 *
8 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
9 */
10
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/string.h>
15 #include <linux/errno.h>
16 #include <linux/if_arp.h>
17 #include <linux/netdevice.h>
18 #include <linux/init.h>
19 #include <linux/skbuff.h>
20 #include <linux/moduleparam.h>
21 #include <net/dst.h>
22 #include <net/neighbour.h>
23 #include <net/pkt_sched.h>
24
25 /*
26 How to setup it.
27 ----------------
28
29 After loading this module you will find a new device teqlN
30 and new qdisc with the same name. To join a slave to the equalizer
31 you should just set this qdisc on a device f.e.
32
33 # tc qdisc add dev eth0 root teql0
34 # tc qdisc add dev eth1 root teql0
35
36 That's all. Full PnP 8)
37
38 Applicability.
39 --------------
40
41 1. Slave devices MUST be active devices, i.e., they must raise the tbusy
42 signal and generate EOI events. If you want to equalize virtual devices
43 like tunnels, use a normal eql device.
44 2. This device puts no limitations on physical slave characteristics
45 f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
46 Certainly, large difference in link speeds will make the resulting
47 eqalized link unusable, because of huge packet reordering.
48 I estimate an upper useful difference as ~10 times.
49 3. If the slave requires address resolution, only protocols using
50 neighbour cache (IPv4/IPv6) will work over the equalized link.
51 Other protocols are still allowed to use the slave device directly,
52 which will not break load balancing, though native slave
53 traffic will have the highest priority. */
54
55 struct teql_master
56 {
57 struct Qdisc_ops qops;
58 struct net_device *dev;
59 struct Qdisc *slaves;
60 struct list_head master_list;
61 struct net_device_stats stats;
62 };
63
64 struct teql_sched_data
65 {
66 struct Qdisc *next;
67 struct teql_master *m;
68 struct neighbour *ncache;
69 struct sk_buff_head q;
70 };
71
72 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
73
74 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT|IFF_BROADCAST)
75
76 /* "teql*" qdisc routines */
77
78 static int
79 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
80 {
81 struct net_device *dev = sch->dev;
82 struct teql_sched_data *q = qdisc_priv(sch);
83
84 if (q->q.qlen < dev->tx_queue_len) {
85 __skb_queue_tail(&q->q, skb);
86 sch->bstats.bytes += skb->len;
87 sch->bstats.packets++;
88 return 0;
89 }
90
91 kfree_skb(skb);
92 sch->qstats.drops++;
93 return NET_XMIT_DROP;
94 }
95
96 static int
97 teql_requeue(struct sk_buff *skb, struct Qdisc* sch)
98 {
99 struct teql_sched_data *q = qdisc_priv(sch);
100
101 __skb_queue_head(&q->q, skb);
102 sch->qstats.requeues++;
103 return 0;
104 }
105
106 static struct sk_buff *
107 teql_dequeue(struct Qdisc* sch)
108 {
109 struct teql_sched_data *dat = qdisc_priv(sch);
110 struct sk_buff *skb;
111
112 skb = __skb_dequeue(&dat->q);
113 if (skb == NULL) {
114 struct net_device *m = dat->m->dev->qdisc->dev;
115 if (m) {
116 dat->m->slaves = sch;
117 netif_wake_queue(m);
118 }
119 }
120 sch->q.qlen = dat->q.qlen + dat->m->dev->qdisc->q.qlen;
121 return skb;
122 }
123
124 static __inline__ void
125 teql_neigh_release(struct neighbour *n)
126 {
127 if (n)
128 neigh_release(n);
129 }
130
131 static void
132 teql_reset(struct Qdisc* sch)
133 {
134 struct teql_sched_data *dat = qdisc_priv(sch);
135
136 skb_queue_purge(&dat->q);
137 sch->q.qlen = 0;
138 teql_neigh_release(xchg(&dat->ncache, NULL));
139 }
140
141 static void
142 teql_destroy(struct Qdisc* sch)
143 {
144 struct Qdisc *q, *prev;
145 struct teql_sched_data *dat = qdisc_priv(sch);
146 struct teql_master *master = dat->m;
147
148 if ((prev = master->slaves) != NULL) {
149 do {
150 q = NEXT_SLAVE(prev);
151 if (q == sch) {
152 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
153 if (q == master->slaves) {
154 master->slaves = NEXT_SLAVE(q);
155 if (q == master->slaves) {
156 master->slaves = NULL;
157 spin_lock_bh(&master->dev->queue_lock);
158 qdisc_reset(master->dev->qdisc);
159 spin_unlock_bh(&master->dev->queue_lock);
160 }
161 }
162 skb_queue_purge(&dat->q);
163 teql_neigh_release(xchg(&dat->ncache, NULL));
164 break;
165 }
166
167 } while ((prev = q) != master->slaves);
168 }
169 }
170
171 static int teql_qdisc_init(struct Qdisc *sch, struct rtattr *opt)
172 {
173 struct net_device *dev = sch->dev;
174 struct teql_master *m = (struct teql_master*)sch->ops;
175 struct teql_sched_data *q = qdisc_priv(sch);
176
177 if (dev->hard_header_len > m->dev->hard_header_len)
178 return -EINVAL;
179
180 if (m->dev == dev)
181 return -ELOOP;
182
183 q->m = m;
184
185 skb_queue_head_init(&q->q);
186
187 if (m->slaves) {
188 if (m->dev->flags & IFF_UP) {
189 if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT))
190 || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST))
191 || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST))
192 || dev->mtu < m->dev->mtu)
193 return -EINVAL;
194 } else {
195 if (!(dev->flags&IFF_POINTOPOINT))
196 m->dev->flags &= ~IFF_POINTOPOINT;
197 if (!(dev->flags&IFF_BROADCAST))
198 m->dev->flags &= ~IFF_BROADCAST;
199 if (!(dev->flags&IFF_MULTICAST))
200 m->dev->flags &= ~IFF_MULTICAST;
201 if (dev->mtu < m->dev->mtu)
202 m->dev->mtu = dev->mtu;
203 }
204 q->next = NEXT_SLAVE(m->slaves);
205 NEXT_SLAVE(m->slaves) = sch;
206 } else {
207 q->next = sch;
208 m->slaves = sch;
209 m->dev->mtu = dev->mtu;
210 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
211 }
212 return 0;
213 }
214
215
216 static int
217 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
218 {
219 struct teql_sched_data *q = qdisc_priv(dev->qdisc);
220 struct neighbour *mn = skb->dst->neighbour;
221 struct neighbour *n = q->ncache;
222
223 if (mn->tbl == NULL)
224 return -EINVAL;
225 if (n && n->tbl == mn->tbl &&
226 memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
227 atomic_inc(&n->refcnt);
228 } else {
229 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
230 if (IS_ERR(n))
231 return PTR_ERR(n);
232 }
233 if (neigh_event_send(n, skb_res) == 0) {
234 int err;
235
236 read_lock(&n->lock);
237 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
238 n->ha, NULL, skb->len);
239 read_unlock(&n->lock);
240
241 if (err < 0) {
242 neigh_release(n);
243 return -EINVAL;
244 }
245 teql_neigh_release(xchg(&q->ncache, n));
246 return 0;
247 }
248 neigh_release(n);
249 return (skb_res == NULL) ? -EAGAIN : 1;
250 }
251
252 static inline int teql_resolve(struct sk_buff *skb,
253 struct sk_buff *skb_res, struct net_device *dev)
254 {
255 if (dev->header_ops == NULL ||
256 skb->dst == NULL ||
257 skb->dst->neighbour == NULL)
258 return 0;
259 return __teql_resolve(skb, skb_res, dev);
260 }
261
262 static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
263 {
264 struct teql_master *master = netdev_priv(dev);
265 struct Qdisc *start, *q;
266 int busy;
267 int nores;
268 int len = skb->len;
269 int subq = skb_get_queue_mapping(skb);
270 struct sk_buff *skb_res = NULL;
271
272 start = master->slaves;
273
274 restart:
275 nores = 0;
276 busy = 0;
277
278 if ((q = start) == NULL)
279 goto drop;
280
281 do {
282 struct net_device *slave = q->dev;
283
284 if (slave->qdisc_sleeping != q)
285 continue;
286 if (netif_queue_stopped(slave) ||
287 __netif_subqueue_stopped(slave, subq) ||
288 !netif_running(slave)) {
289 busy = 1;
290 continue;
291 }
292
293 switch (teql_resolve(skb, skb_res, slave)) {
294 case 0:
295 if (netif_tx_trylock(slave)) {
296 if (!netif_queue_stopped(slave) &&
297 !__netif_subqueue_stopped(slave, subq) &&
298 slave->hard_start_xmit(skb, slave) == 0) {
299 netif_tx_unlock(slave);
300 master->slaves = NEXT_SLAVE(q);
301 netif_wake_queue(dev);
302 master->stats.tx_packets++;
303 master->stats.tx_bytes += len;
304 return 0;
305 }
306 netif_tx_unlock(slave);
307 }
308 if (netif_queue_stopped(dev))
309 busy = 1;
310 break;
311 case 1:
312 master->slaves = NEXT_SLAVE(q);
313 return 0;
314 default:
315 nores = 1;
316 break;
317 }
318 __skb_pull(skb, skb_network_offset(skb));
319 } while ((q = NEXT_SLAVE(q)) != start);
320
321 if (nores && skb_res == NULL) {
322 skb_res = skb;
323 goto restart;
324 }
325
326 if (busy) {
327 netif_stop_queue(dev);
328 return 1;
329 }
330 master->stats.tx_errors++;
331
332 drop:
333 master->stats.tx_dropped++;
334 dev_kfree_skb(skb);
335 return 0;
336 }
337
338 static int teql_master_open(struct net_device *dev)
339 {
340 struct Qdisc * q;
341 struct teql_master *m = netdev_priv(dev);
342 int mtu = 0xFFFE;
343 unsigned flags = IFF_NOARP|IFF_MULTICAST;
344
345 if (m->slaves == NULL)
346 return -EUNATCH;
347
348 flags = FMASK;
349
350 q = m->slaves;
351 do {
352 struct net_device *slave = q->dev;
353
354 if (slave == NULL)
355 return -EUNATCH;
356
357 if (slave->mtu < mtu)
358 mtu = slave->mtu;
359 if (slave->hard_header_len > LL_MAX_HEADER)
360 return -EINVAL;
361
362 /* If all the slaves are BROADCAST, master is BROADCAST
363 If all the slaves are PtP, master is PtP
364 Otherwise, master is NBMA.
365 */
366 if (!(slave->flags&IFF_POINTOPOINT))
367 flags &= ~IFF_POINTOPOINT;
368 if (!(slave->flags&IFF_BROADCAST))
369 flags &= ~IFF_BROADCAST;
370 if (!(slave->flags&IFF_MULTICAST))
371 flags &= ~IFF_MULTICAST;
372 } while ((q = NEXT_SLAVE(q)) != m->slaves);
373
374 m->dev->mtu = mtu;
375 m->dev->flags = (m->dev->flags&~FMASK) | flags;
376 netif_start_queue(m->dev);
377 return 0;
378 }
379
380 static int teql_master_close(struct net_device *dev)
381 {
382 netif_stop_queue(dev);
383 return 0;
384 }
385
386 static struct net_device_stats *teql_master_stats(struct net_device *dev)
387 {
388 struct teql_master *m = netdev_priv(dev);
389 return &m->stats;
390 }
391
392 static int teql_master_mtu(struct net_device *dev, int new_mtu)
393 {
394 struct teql_master *m = netdev_priv(dev);
395 struct Qdisc *q;
396
397 if (new_mtu < 68)
398 return -EINVAL;
399
400 q = m->slaves;
401 if (q) {
402 do {
403 if (new_mtu > q->dev->mtu)
404 return -EINVAL;
405 } while ((q=NEXT_SLAVE(q)) != m->slaves);
406 }
407
408 dev->mtu = new_mtu;
409 return 0;
410 }
411
412 static __init void teql_master_setup(struct net_device *dev)
413 {
414 struct teql_master *master = netdev_priv(dev);
415 struct Qdisc_ops *ops = &master->qops;
416
417 master->dev = dev;
418 ops->priv_size = sizeof(struct teql_sched_data);
419
420 ops->enqueue = teql_enqueue;
421 ops->dequeue = teql_dequeue;
422 ops->requeue = teql_requeue;
423 ops->init = teql_qdisc_init;
424 ops->reset = teql_reset;
425 ops->destroy = teql_destroy;
426 ops->owner = THIS_MODULE;
427
428 dev->open = teql_master_open;
429 dev->hard_start_xmit = teql_master_xmit;
430 dev->stop = teql_master_close;
431 dev->get_stats = teql_master_stats;
432 dev->change_mtu = teql_master_mtu;
433 dev->type = ARPHRD_VOID;
434 dev->mtu = 1500;
435 dev->tx_queue_len = 100;
436 dev->flags = IFF_NOARP;
437 dev->hard_header_len = LL_MAX_HEADER;
438 }
439
440 static LIST_HEAD(master_dev_list);
441 static int max_equalizers = 1;
442 module_param(max_equalizers, int, 0);
443 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
444
445 static int __init teql_init(void)
446 {
447 int i;
448 int err = -ENODEV;
449
450 for (i = 0; i < max_equalizers; i++) {
451 struct net_device *dev;
452 struct teql_master *master;
453
454 dev = alloc_netdev(sizeof(struct teql_master),
455 "teql%d", teql_master_setup);
456 if (!dev) {
457 err = -ENOMEM;
458 break;
459 }
460
461 if ((err = register_netdev(dev))) {
462 free_netdev(dev);
463 break;
464 }
465
466 master = netdev_priv(dev);
467
468 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
469 err = register_qdisc(&master->qops);
470
471 if (err) {
472 unregister_netdev(dev);
473 free_netdev(dev);
474 break;
475 }
476
477 list_add_tail(&master->master_list, &master_dev_list);
478 }
479 return i ? 0 : err;
480 }
481
482 static void __exit teql_exit(void)
483 {
484 struct teql_master *master, *nxt;
485
486 list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
487
488 list_del(&master->master_list);
489
490 unregister_qdisc(&master->qops);
491 unregister_netdev(master->dev);
492 free_netdev(master->dev);
493 }
494 }
495
496 module_init(teql_init);
497 module_exit(teql_exit);
498
499 MODULE_LICENSE("GPL");
Linux 2.6 libata-dev (mirror)